This invention relates to internal combustion engines, especially to internal combustion engines that can be used in mobile vehicles, including, but not limited to, automobiles, aircraft and boats. This invention also relates to internal combustion engines in which multiple pistons are joined as part of a rigid subassembly.
A four cylinder horizontally opposed “Flat Four” or “Boxer” engine includes four cylinders, which are mounted horizontally in opposed pairs. The term “Boxer Engine” describes the motion of the four pistons as they move back and forth in opposing pairs, much like a boxer's arms. This engine was first introduced in the late 1930's. The horizontally opposed layout of the cylinders helped to balance out the forces exerted on the crankshaft by the moving pistons and the connecting rods, which connected each individual piston to a centrally mounted crankshaft. Although pistons were located on opposite sides of a central crankshaft, opposed pistons did not move along the same axis, and the four pistons moved along four parallel axes, which intersect the crankshaft at different lateral positions. Unlike the present invention, each of the pistons comprised a separate member with its own connecting rod, which moves angularly relative to both the crankshaft and the piston.
U.S. Pat. No. 6,082,314 discloses another type of opposed cylinder internal combustion engine. In this patent four cylinders are arranged in an H-shaped configuration. Two double acting or double-ended pistons, each with generally cylindrically shaped crowns on opposite sides of flat rectangular parallelepiped middle sections, are mounted on a crank shaft so that each double acting piston reciprocates in opposed cylinders. The two double acting pistons, each of which is part of a one-piece member with piston crowns at either end, move in the same direction during each stroke, and circular slide blocks, eccentrically mounted on the crank shaft, are received in openings between the piston crowns to replace connecting rods. A dynamic balance slide piece reciprocates along an axis perpendicular to the piston reciprocation. The SYTEC engine proposed by CMC Research House at the Department of Mechanical & Manufacturing Engineering of the University of Melbourne also includes a bearing block that moves perpendicular to the motion of two double-ended, single piece pistons connected to a central crankshaft.
U.S. Pat. No. 2,370,902 also discloses multiple sets of double-ended pistons that move in the same direction during each stroke. In this case, connecting rods rigidly connected to pistons at opposite ends are themselves interconnected by a cross bar. Anti-friction rollers mounted on a slide bar secured to the cross bar move with the double ended pistons and engage cams in the form of star shaped plates to impart rotation to a drive shaft.
In U.S. Pat. No. 4,011,842, a pair of spaced parallel, double-ended cylinders straddle a crankshaft and two double-ended pistons are connected to the crankshaft by a T-shaped connecting member so that linear motion of the double-ended pistons causes rotation of the crankshaft. The two doubled-ended pistons move in opposite directions. U.S. Pat. No. 6,446,587 and U.S. Pat. No. 6,073,595 are other examples of internal combustion engines with double-ended pistons moving in opposite directions.
It has been suggested that internal combustion engines with double-ended pistons can also be used to produce an electrical current. In U.S. Pat. No. 6,532,916 an oscillating alternator coil attached to a moving double-ended piston in an internal combustion engine moves through a magnetic field imparted by a stationary magnet. In some small internal combustion engines and alternator often comprises a ring of magnets mounted on a rotating flywheel, which act in conjunction with stationary core and windings on the engine body. Two examples of such devices are shown in U.S. Pat. No. 3,828,212 and U.S. Pat. No. 4,101,371.
The instant invention is believed to include many of the advantageous features represented by these examples of the prior art, but achieves these improvements by employing a configuration in which the components are easier to fabricate and in which assembly is simpler. The instant invention should therefore be easier to service since assembly and disassembly are more straightforward. The anticipated life and reliability of the engine constructed according to this invention should also be significantly greater than has heretofore been possible with more elaborate engine configurations. Relative movement of component parts of this engine is believed to place less stress on moving parts, and these moving parts can be lubricated more efficiently and more effectively. The efficiency that can be achieved with this inventive configuration is also believed to be superior to that which can be achieved with conventional internal combustion engine configurations. In view of the simplicity of the basic operation of this engine, excessive vibration should not be a problem. In spite of the effort that has been expended to improve the performance of conventional internal combustion engine configurations, the piston slide body configuration of the instant invention should offer these and other advantages over these and other prior art configurations.